Relief of congestive symptoms is a primary goal in treating heart failure. Ultrafiltration is a tool that can be used to safely remove sodium and water from whole blood at a controlled rate. Ultrafiltration decreases symptoms, relieves congestion, and improves hemodynamics, neurohormonal balance, and exercise capacity. This article describes the importance of congestion as a therapeutic target in heart failure and outlines the development of ultrafiltration as a treatment to address this important physiologic state.